The suspect, identified bymedia as Robert Murat, was living roughly 100 metres from the hotel bedroom where Madeleine McCann slept the evening of May 3, before she disappeared from the resort where her family was vacationing. At the time, Madeleine's parents were eating supper at a restaurant 50 metres away.

Police questionedthe suspectlate into Monday evening but released him because there was not enough evidence to file charges against him, police inspector Olegario deSousasaid Tuesday.

Investigators also seized some of his belongings,de Sousa said. He did not identify the suspect's name or nationality.

Muratwas reportedly among three others questioned, including a German woman and a Portuguese man. Those threewere released overnight.

The stocky, bespectacled Murat was known to police and to media in Portugal because he volunteered to act as an interpreter during the investigations and ground search in the immediate days following Madeleine's disappearance. He told journalists that he had a daughter in England who reminded him of the missing girl.

But Murat's enthusiasm in assisting with the search raised the eyebrows of Sunday Mirror reporter Lori Campbell, who tipped off police after she spoke to him.

"He surfaced on Friday afternoon last week and was walking around as if he was somebody official," Campbell told Portuguese television. "He claimed that he was just a local guy who spoke fluent Portuguese and English and was helping the family. When I was talking to him, he was very vague about his purpose."

According to some reports,forensics teamsalso searched the Casa Liliana villa where Muratlives with his 71-year-old mother, Jenny, and drained the swimming pool.

Being named formally as a suspect does not necessarily mean Murat has been accused of a crime, although he can be referred to as a defendant. Under Portuguese law, he is now a part of the judicial process and can also act as a vital witness in the case.